Wireless base stations operating using one or more dielectric filters comprised of resonator “pucks” are becoming more common because of increasing demands for filtering of signals both on the transmit and receive sides. Dielectric-based resonators are attractive for wireless applications because they have low loss (i.e., high Q values). Unfortunately, there are a number of limitations with current dielectric-based resonators. First, current dielectric materials tend to be very sensitive to temperature changes. As the temperature of the dielectric material changes, the dielectric constant and dimensions of the material will also change, thereby causing an adverse shift in frequency. Second, current filters which are formed from dielectric materials tend to be large and bulky due the large volume of dielectric material needed to form the individual filters. Both of these limitations result in the added cost associated with dielectric filters relative to metal cavity filters
Attempts have been made to combine multiple materials with offsetting temperature properties to compensate for the temperature dependency problems. In this solution, materials with different affects on the dielectric constant are combined in order to stabilize the temperature variations. Unfortunately, this leads to a lowering of the average dielectric constant of the dielectric material. Consequently, a large volume of material is needed in these solutions. Moreover these solutions produce filters with increased overall loss (lower Q values). There also is the disadvantage that actual construction of the filter requires bimetals/multiple metals to compensate for the different thermal properties between the housing (or stage) and the dielectric component.
There thus is a need for a device/method which can reduce or eliminate entirely the adverse temperature dependencies found in current dielectric-based resonators/filters. The device/method preferably allows the use of dielectric materials having high dielectric constants in a range of temperature environments.